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F. SIGRIST. STRUT, SPAR, OR THE LIKE FOR USE IN AIRCRAFT CONSTRUCTION.

APPLICATIGN FILED OCT. 10, I917.

Patented May13, 1919.

INVENTORL "4:; nomus musomruamumo. mumnmou. u c.

UNITED STATES PATENT OFFICE.

FREDERICK SIGRIST, OF KIN G STON-ON-THAMES, ENGLAND.

STRUT, SPAR, on THE LIKE FOR USE IN AIRCRAFT CONSTRUCTION.

Application filed October 10,

To all whom it may concern:

Be it known that I, FREDERICK SIGRIsT, .a subject of the King of Great Britain and Ireland, residing at Kingston-on-Thames, in the county of Surrey, England, have invented a new and useful Improvement in Struts, Spars, or the like for Use in Aircraft Construction, of which the following is a specification.

This invention relates to struts, spars or the like used in the construction of aeroplanes and other aircraft, and it consists in reinforcing such members when made of wood by one or more longitudinally arranged metallic ribs which extend through both the length and the thickness or depth of said strutor spar, the object being to stiffen such struts, spars or the like so that they are able to stand the stresses imposed upon them equally as well as metallic struts or' spars of tubular construction.

In the accompanying drawing which illustrates this invention:- 4

Figure 1 is a view in transverse section of a strut constructed according to the present invention, 7

Fig. 2' is a broken view in plan of an alternative construction, and

Fig. 3 is a broken view in transverse sec tion showing an alternative construction.

Throughout the views similar parts are marked with like letters of reference.

The wooden strut which has any desired exterior shapeis formed of two pieces a and a which on being fixed together edge to edge, form the complete strut. Between these two pieces is placed a metallic rib the depth of which is the same as the thickness or depth of the strut and the length of same is such that it extends through the whole length thereof. The metallic rib is formed of two 'channehshaped plates 72 which are fitted over the inner edges of the pieces a and a the horizontal flanges 6 being let into said pieces so as to preserve the smooth exterior surfaces of the strut.

The various elements of the strut are held and fixed together either by means of a series of transverse tie bolts 0 as shown in Fig. 1 or by wrapping the two pieces a and a when Specification ofQLctters Patent.

Patented May 13, 1919.

19-17. Serial No. 195,809.

in positionto form the complete strut, with a tape 6 or the like of any suitable material as shown in Fig. 2. In the former construction the head 0 of the bolt 0 is suitably shaped to preserve the outline of the rear edge of the strut and the nut c of said bolt is suitably recessed in the front edge of the strut to the same end.

The channel-shaped plates 6 may be individually secured to the two pieces a and a 'by screws or the like.

Although the construction hereinbefore described is what I think is the preferable construction I do not limit myself to the use of a reinforcing rib constructed out of two pieces of channel section as it would be within the spirit and scope of this invention to so combine said'two pieces of channel section asto make an H-shaped rib as shown in Fig. 3 which in effect it becomes when two channel-shaped plates are employed and allthe elements of the strut are fixed to gether.

What I claim as my invention and desire to secure by LettersPatent is 1. A strut, spar or the like for use in the construction of aircraft, comprising two pieces of wood adapted on being placed edge to edge to give the desired exterior shape to the strut, spar or the like, a metallic rib of a double channel section located between said pieces and extending through both the length and the depth or thickness of the strut or spar, and means for fixing and holding said elements together.

2. In a strut, spar or the like for aeroplanes and other aircraft, the combination oftwostrips of wood adapted to be placed edge to edge, a channel-shaped metallic plate adapted to fit on the inner edge of each strip, and means for fixing and holding said elements together.

3. In a strut, spar or the like for aeroplanes and other aircraft, the combination of two strips of wood adapted to be placed edge to edge, a metallic rib of H-section located between the abutting edges of the two strips, and means for fixing and holding said elements together.

4. A strut, spar or the like for use in the construction of aircraft, comprising tWo strips of Wood a and a adapted on being placed edge to edge to give the desired eX- terior shape to the strut, spar or the like, a metallic rib b of girder section located between said strips and extending through both the length and the depth or thickness of the strut or spar, and a series of longitudinally arranged tie bolts 0 for holding the elements of the strut or the like together. 10

In testimony whereof I have signed my name.

FREDERICK SIGRIST.

Copies of this patent may be obtained for five cents each, by addressing the "Commissioner of ratentl. Washington, D. 0. 

